September weather forecastGrass Valley, OR
September
Weather in September
The first month of the autumn, September, is still a pleasant month in Grass Valley, Oregon, with an average temperature ranging between min 52.7°F (11.5°C) and max 73.2°F (22.9°C).Temperature
Grass Valley in September demonstrates a small temperature transition, adjusting from an average high of a moderately hot 83.3°F (28.5°C) in August to an agreeable 73.2°F (22.9°C). During the month of September, the nighttime temperature falls to an average of 52.7°F (11.5°C).Humidity
In Grass Valley, the average relative humidity in September is 54%.Rainfall
In Grass Valley, in September, it is raining for 5.8 days, with typically 0.35" (9mm) of accumulated precipitation. In Grass Valley, during the entire year, the rain falls for 112.2 days and collects up to 10.91" (277mm) of precipitation.Snowfall
April through October are months without snowfall.Daylight
In Grass Valley, Oregon, the average length of the day in September is 12h and 31min.On the first day of the month, sunrise is at 6:25 am and sunset at 7:39 pm. On the last day of September, sunrise is at 7:01 am and sunset at 6:44 pm PDT.
Sunshine
In Grass Valley, the average sunshine in September is 10.8h.UV index
In Grass Valley, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from unprotected exposure to Sun's UV rays for the average person.Note: The maximum daily UV index of 4 in September interprets into the following recommendations:
Heed the precautions - It is counselled to guard against solar damage. Stay safe from the Sun's strongest UV rays by limiting exposure during midday. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Grass Valley, OR
- Average high temperature in September: 73.2°F
The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is December (37.4°F).
- Average low temperature in September: 52.7°F
The month with the highest average low temperature is August (57.9°F).
The coldest month (with the lowest average low temperature) is December (27°F).
Average pressure in September
Grass Valley, OR
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.95"Hg).
Average wind speed in September
Grass Valley, OR
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is June (7.9mph).
The calmest months (with the lowest average wind speed) are January and December (5mph).
Average humidity in September
Grass Valley, OR
- Average humidity in September: 54%
The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is August (46%).
Average rainfall in September
Grass Valley, OR
- Average rainfall in September: 0.35"
The wettest month (with the highest rainfall) is January (1.93").
The driest month (with the least rainfall) is July (0.12").
Average rainfall days in September
Grass Valley, OR
- Average rainfall days in September: 5.8 days
The month with the highest number of rainy days is March (14.3 days).
The month with the least rainy days is July (2.9 days).
Average snowfall in September
Grass Valley, OR
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.87").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Grass Valley, OR
- Average snowfall days in September: 0 days
The months with the highest number of snowfall days are February and December (3.9 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Grass Valley, OR
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).
- Average sunshine in September: 10h and 48min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 0min).
Average sunshine days in September
Grass Valley, OR
- Average sunshine days in September: 22.3 days
The month with the most sunshine days is July (27 days).
The month with the least sunshine days is February (12.3 days).
Average UV index in September
Grass Valley, OR
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Grass Valley, OR
- Average cloud cover in September: 17
The month with the most cloud cover is January (Cloud cover 49).
The months with the least cloud cover are July and August (Cloud cover 9).
Average visibility in September
Grass Valley, OR
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (5mi).
